Method of producing dicalcium phosphate.



EUGEN BERGMANN, OF OHLAU, GERMANY.

METHOD OF PRODUCING DICALCIUIVI PHOSPHATE.

Specification of Letters Patent.

Patented April 30, 1907.

Original application filed October 13, 1903, Serial No.1'76,873. Divided and this application filed May 1'1 1904. Serial No. 207,428.

To alt whom, it may concern.-

Be it known that I, EUGEN BERGMANN, manufacturer, a citizen of the German Empire, residing at Ohlau, Silesia, Germany, have invented a new or Improved Method of Producing Dicalcium Phosphate, of which the following is a specification.

This invention relates to a method of pro: ducing dicalcium phosphate by usingthe known reaction whereby tricalcium phosphate is dissolved in cold aqueous sulfurous acid and the sulfurous acid is then eliminated from such solution by boiling.

(Compare llagners J ahresber'icht 1882, pa e 389. Investigations by Rotondi). The icalcium phosphate obtained by such reaction has the disadvanta e that the precipitate contains calcium su fite, which appears J to render its suitability as an ingredient for cattle food doubtful, as no investigations have been made on the action of sullites on the stomachs of animals.

In order to obtain a dicalcium phosphate free from the sulfite of calcium, this invention provides an addition of acid (for instance phosphor c acld, hydrochloric acid, sulfuric acld or blsulfate of sodium having an analogous actlon) to the aforesaid solution of tr -phosphate of lune or to the precipitate obtained by its being boiled. For instance:

(1 Sulfuric acid:

Solution Addition caugrop,+2oa uso, ,+n,so,=

' Precipitate oaso,+2oaHPo,+4H o+4so b) llydrochloric acid:

Solution Addition CaI-lAPOQ +2Ca(llS0 +2HOl= Precipitate 2oauPo,+4n,o+4so +oao1,.

I c) Phosphoric acid:

Addition (,all (PO +2Ua(lrlSO +H PO 3oain o,+4no,+4so,. The sulfurous acid must be expelled by boiling, as in the cold, the latter would cause the reformation of monocalcium phosphate and calcium bisulfite.

This process is distinguished from the known method of producing calciumphosphate from a solution of tricalcium phosphate in cold 'of lime becomes necessary. In the present invention however the expense of lime as a means of precipitating is done awaywith. By these means dlcalcium phosphate can be produced from a solution of tricalcium phosphate in cold hydrated sulfurous acid or from the precipitate obtained from such solution by boiling, the distinctive feature whereof is that a mineral acid is added to, the reaction mixture and the sulfurous acid is then eliminated by boilin Havin now particularfy described and ascertaine the nature of my invention and in what manner the same is performed, I declare that what I claim is:

1. In the process of manufacturing dicalcium phosphate by treating tricalcium phosphate with aqueous sulfurous acid and eliminating the sulfurous acid by boiling, the improvement which consists in decom osing the calcium sulfite by adding a minera acid.

2. The process of manufacturing dicalcium phosphate, which consists of boilmg a solution of tricalcium phosphate in aqueous sulfurous acid formin a precipitate containing calcium sulfite, adc ing a mineral acid to the precipitate and subsequently boiling this mixture for the purpose of obtaining a precipitate free from ca cium sulfite.

In testimony whereof I have signed this specification in the presence of two subscribing witnesses.

EUGEN BERGMANN.

Witnesses:

A. W. M AN, ALBERT SOHENK. 

